<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<script>
		
		console.log(Math)
		console.log(Math.abs(-90))
		console.log(Math.ceil(12.00000001)) //向上
		console.log(Math.floor(12.99999)) //向上
		console.log(Math.round(12.51)) //向上

		console.log(Math.round(Math.random()*100)); //0-1  35  0-35 0+1 36+1
		// 
	 // 5-20
	 	max = 10;
	 	min = 5;

		res = Math.round((Math.random()*(max-min))+min);

		document.write(res);


		// 1:: 1-49 封装，7个不重复的数
 
	</script>
</head>
<body>
	
</body>
</html>